rM2: hwmon: Copy the rM2 sy7636a-hwmon driver

Copy the rM2 zero-sugar branch
(https://github.com/reMarkable/linux/tree/zero-sugar) to the new kernel.

Signed-off-by: Alistair Francis <alistair@alistair23.me>

drivers/hwmon/Kconfig

@@ -1424,6 +1424,16 @@ config SENSORS_SIS5595
 	  This driver can also be built as a module. If so, the module
 	  will be called sis5595.
 
+config SENSORS_SY7636A
+	tristate "Silergy SY7636A"
+	depends on I2C
+	help
+	  If you say yes here you get support for the thermistor readout of
+	  the Silergy SY7636A PMIC.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called sy7636a-hwmon.
+
 config SENSORS_DME1737
 	tristate "SMSC DME1737, SCH311x and compatibles"
 	depends on I2C && !PPC

drivers/hwmon/Makefile

@@ -159,6 +159,7 @@ obj-$(CONFIG_SENSORS_SMSC47B397)+= smsc47b397.o
 obj-$(CONFIG_SENSORS_SMSC47M1)	+= smsc47m1.o
 obj-$(CONFIG_SENSORS_SMSC47M192)+= smsc47m192.o
 obj-$(CONFIG_SENSORS_STTS751)	+= stts751.o
+obj-$(CONFIG_SENSORS_SY7636A)	+= sy7636a-hwmon.o
 obj-$(CONFIG_SENSORS_AMC6821)	+= amc6821.o
 obj-$(CONFIG_SENSORS_TC74)	+= tc74.o
 obj-$(CONFIG_SENSORS_THMC50)	+= thmc50.o

drivers/hwmon/sy7636a-hwmon.c

@@ -0,0 +1,105 @@
+/*
+ * Functions to access SY3686A power management chip temperature
+ *
+ * Copyright (C) 2019 reMarkable AS - http://www.remarkable.com/
+ *
+ * Author: Lars Ivar Miljeteig <lars.ivar.miljeteig@remarkable.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/jiffies.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/err.h>
+#include <linux/sysfs.h>
+#include <linux/platform_device.h>
+
+#include <linux/mfd/sy7636a.h>
+
+struct sy7636a_data {
+	struct sy7636a *sy7636a;
+	struct device *hwmon_dev;
+};
+
+static ssize_t show_temp(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	unsigned int reg_val;
+	signed char temp;
+	int ret;
+	struct sy7636a_data *data = dev_get_drvdata(dev);
+
+	ret = regmap_read(data->sy7636a->regmap,
+			SY7636A_REG_TERMISTOR_READOUT, &reg_val);
+	if (ret)
+		return ret;
+
+	temp = *((signed char*)&reg_val);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", temp);
+}
+
+static SENSOR_DEVICE_ATTR(temp0, S_IRUGO, show_temp, NULL, 0);
+
+static struct attribute *sy7636a_attrs[] = {
+	&sensor_dev_attr_temp0.dev_attr.attr,
+	NULL
+};
+
+ATTRIBUTE_GROUPS(sy7636a);
+
+static int sy7636a_sensor_probe(struct platform_device *pdev)
+{
+	struct sy7636a *sy7636a = dev_get_drvdata(pdev->dev.parent);
+	struct sy7636a_data *data;
+	int err;
+
+	if (!sy7636a)
+		return -EPROBE_DEFER;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(struct sy7636a_data), GFP_KERNEL);
+	if (!data) {
+		return -ENOMEM;
+	}
+
+	data->sy7636a = sy7636a;
+	data->hwmon_dev = devm_hwmon_device_register_with_groups(&pdev->dev,
+			"sy7636a_temperature", data, sy7636a_groups);
+	if (IS_ERR(data->hwmon_dev)) {
+		err = PTR_ERR(data->hwmon_dev);
+		dev_err(&pdev->dev, "Unable to register hwmon device, returned %d", err);
+		return err;
+	}
+
+	return 0;
+}
+
+static const struct platform_device_id sy7636a_sensor_id[] = {
+	{ "sy7636a-temperature", 0},
+	{ },
+};
+MODULE_DEVICE_TABLE(platform, sy7636a_sensor_id);
+
+static struct platform_driver sy7636a_sensor_driver = {
+	.probe = sy7636a_sensor_probe,
+	.id_table = sy7636a_sensor_id,
+	.driver = {
+		.name = "sy7636a-temperature",
+	},
+};
+module_platform_driver(sy7636a_sensor_driver);
+
+MODULE_AUTHOR("Lars Ivar Miljeteig <lars.ivar.miljeteig@remarkable.com>");
+MODULE_DESCRIPTION("Silergy SY7636A Sensor Driver");
+MODULE_LICENSE("GPL v2");

include/linux/mfd/sy7636a.h

@@ -0,0 +1,49 @@
+/*
+ * Functions to access SY3686A power management chip.
+ *
+ * Copyright (C) 2019 reMarkable AS - http://www.remarkable.com/
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __LINUX_MFD_SY7636A_H
+#define __LINUX_MFD_SY7636A_H
+
+#include <linux/i2c.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+#include <linux/regmap.h>
+
+#define SY7636A_REG_OPERATION_MODE_CRL 0x00
+#define SY7636A_OPERATION_MODE_CRL_VCOMCTL (1 << 6)
+#define SY7636A_OPERATION_MODE_CRL_ONOFF (1 << 7)
+#define SY7636A_REG_VCOM_ADJUST_CTRL_L 0x01
+#define SY7636A_REG_VCOM_ADJUST_CTRL_H 0x02
+#define SY7636A_REG_VCOM_ADJUST_CTRL_MASK 0x01ff
+#define SY7636A_REG_VLDO_VOLTAGE_ADJULST_CTRL 0x03
+#define SY7636A_REG_POWER_ON_DELAY_TIME 0x06
+#define SY7636A_REG_FAULT_FLAG 0x07
+#define SY7636A_FAULT_FLAG_PG (1 << 0)
+#define SY7636A_REG_TERMISTOR_READOUT 0x08
+
+#define SY7636A_REG_MAX 0x08
+
+struct sy7636a {
+	struct device *dev;
+	struct regmap *regmap;
+	unsigned int vcom;
+	struct gpio_desc *pgood_gpio;
+	struct mutex reglock;
+};
+
+int get_vcom_voltage_mv(struct regmap *regmap);
+int set_vcom_voltage_mv(struct regmap *regmap, unsigned int vcom);
+
+#endif /* __LINUX_MFD_SY7636A_H */